Types of Tankers

Oil tankers are loosely classified based on their carrying capacity in deadweight tons (DWT), which is the total weight of the ship (including cargo, crew, provisions, etc.) minus the weight of the ship if it were empty. It is likely that attackers would focus on the largest tankers to maximize their effect on the global oil market.

Very large crude carriers (VLCC), first developed in the 1960s, have a capacity of over 200,000 DWT and can carry two million barrels of oil. Ultra large crude carriers (ULCC) can carry in excess of 320,000 DWT, roughly three million barrels of oil. Other categories of tankers include: Medium Range (MR), Panamax (the largest tankers that can fit through the Panama Canal), Aframax, and Suezmax (the largest tankers that can fit through the Suez Canal).

Breakdown of Various Classifications of Oil Tankers

Size / Classification

Deadweight Tonnage (DWT)

Avg Dimension (Length | Height | Draft in feet)

Average DWT / vessel[i]

Approx # of vessels[ii]

# of Orders in 2006[iii]

Medium Range

25,000 - 50,000

675 | 100 | 55

41,000

1273

330

Panamax

50,000 - 75,000

65,000

~809

46

Aframax

75,000 - 120,000

810 | 110 | 60

106,000

~900

160

Suezmax

120,000 - 180,000

950 | 150 | 60

161,000

~600

83

VLCC

200,000 - 320,000

1240 | 200 | 100

306,000

474

102

ULCC

320,000+

86,000

4056

720

Most of the crude oil carriers that currently travel through the Strait of Hormuz are VLCCs carrying oil to markets in East Asia. A few smaller oil tankers make "quick" runs to India and other closer destinations. But of course tankers are flexible: pretty much any ocean-going tanker can transport crude oil from the Persian Gulf to any part of the world, depending on market conditions.